Rhodobacter capsulatus genes encoding form I ribulose-1,5-bisphosphate carboxylase/oxygenase (cbbLS) and neighbouring genes were acquired by a horizontal gene transfer.
Analysis of the nucleotide sequence of the form I ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) genes (cbbL and cbbS) of the non-sulfur purple bacterium Rhodobacter capsulatus indicated that the deduced amino acid sequence of the large subunit was not closely homologous to the large subunit from related organisms. Indeed, phylogenetic analysis suggested that the large subunit protein (CbbL) more closely resembled the enzyme from alpha/beta/gamma purple bacteria and cyanobacteria and is within a 'green-like' radiation of the RubisCO phylogenetic tree, well separated from CbbL of the related organism Rhodobacter sphaeroides. A cbbQ gene was discovered downstream of cbbS in Rh. capsulatus, a gene arrangement which also appears to be limited to certain organisms containing a 'green-like' RubisCO. Upstream, and divergently transcribed from cbbLSQ, is a gene (cbbRI) that encodes a LysR-type transcriptional activator. Phylogenetic analysis of the deduced amino acid sequence of CbbRI also suggests that this protein is quite distinct from the Rh. sphaeroides CbbR protein, and is even distinct from the previously described CbbRII protein, the gene of which is upstream and divergently transcribed from the cbbII operon of Rh. capsulatus. Interestingly, Rh. capsulatus CbbRI is more closely related to CbbR from bacteria whose RubisCO falls within the 'green-like' radiation of the CbbL tree. These studies suggest that the cbbRI-cbbL-cbbS-cbbQ genes were acquired by Rh. capsulatus via horizontal gene transfer from a bacterial species containing a 'green-like' RubisCO.
Paoli
George C
GC
The Department of Microbiology and Plant Molecular Biology/Biotechnology Program, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210-1292, USA.
Soyer
Ferda
F
Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA.
Shively
Jessup
J
Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA.
Tabita
F Robert
FR
The Department of Microbiology and Plant Molecular Biology/Biotechnology Program, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210-1292, USA.
D000595:Amino Acid Sequence; D002874:Chromosome Mapping; D022761:Gene Transfer, Horizontal; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D010802:Phylogeny; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D015183:Restriction Mapping; D016354:Rhodobacter capsulatus / Q000201:enzymology* / Q000235:genetics*; D012242:Rhodobacter sphaeroides / Q000737:chemistry / Q000235:genetics; D012273:Ribulose-Bisphosphate Carboxylase / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics*; D016415:Sequence Alignment; D017385:Sequence Homology; D015534:Trans-Activators / Q000096:biosynthesis / Q000235:genetics; D014158:Transcription, Genetic
D046911:Macromolecular Substances; D011994:Recombinant Proteins; D015534:Trans-Activators; D012273:Ribulose-Bisphosphate Carboxylase